1. Field of Invention
The present invention relates to motor vehicles and more particularly to powering systems that use the vehicle engine to power a vehicle carried auxiliary mechanism and more particularly a paper shredder.
2. Background and Description of Prior Art
Commercial truck type motor vehicles are often equipped with auxiliary mechanical systems that use the vehicle engine to power the auxiliary system such as water pumps on fire trucks, trash compactors on refuse collection trucks and paper shredders on office waste removal trucks. Trucks equipped with such auxiliary mechanical systems generally power the auxiliary system with power takeoff (PTO) equipment that, at the selection of the operator, directs power from the vehicle engine to the auxiliary system.
Commonly PTO equipment is hydraulically activated which requires hydraulic pumps interconnected with a vehicle power train by a gearbox or other mechanical linkage, hydraulic hoses with related valves and fittings, and a reservoir having a cooler for hydraulic oil. As a result, hydraulic PTO systems are complex, bulky, and heavy. Although hydraulic systems provide substantial amounts of torque, such systems generally do not generate high rotary speeds.
PTO mechanisms may also be mechanical with plural interconnecting gears, clutches and shafts, commonly called a PTO transmission. PTO transmissions are generally able to generate higher rotary speed levels than hydraulic PTO systems, but they are generally more complex and have greater mechanical wear. PTO transmissions are also generally heavy, bulky, and typically are available only as original equipment on vehicles which makes retrofitting a truck with a PTO transmission to power an auxiliary system expensive and difficult.
Another drawback to known hydraulic PTO systems and PTO transmissions is noise, especially when either mechanism is powering a paper shredding apparatus. Typically the noise is characterized by a “high pitched squeal” caused by the hydraulic fluid passage and motion of PTO system components. Because paper shredding operations are frequently conducted in urban areas, noise is a regulatory problem because it is classified as “pollution” in some jurisdictions. Additionally, the bulkiness and weight of known hydraulic PTO systems and PTO transmissions reduce the amount of shredded paper a truck may carry. Because commercial trucks are limited in weight carrying capacity, a lighter and smaller PTO system increases the amount of shredded paper that may be carried to increase productivity. Further, a large reservoir of hydraulic fluid poses a spill risk in the event of a vehicular accident or mechanical breakdown posing an environmental risk.
Paper shredding systems also require auxiliary mechanisms to move unshredded paper into a storage area prior to shredding, to feed the paper to a shredder, to move the shredded paper to a storage area and to unload shredded paper from the storage area. In known paper shredding systems these auxiliary mechanisms are generally power by hydraulic rams to further increase the bulk and weight of the paper shredding system, responsively reducing the amount of shredded paper the truck may carry and increasing the number of fastenings and fittings where a spillage of hydraulic fluid may occur.
The instant invention seeks to resolve these and other disadvantages inherent in known PTO systems and PTO transmissions by using an endless flexible belt transmission system communicating with the vehicle drive shaft to power a PTO assembly. A gear range selector on a vehicle's multi-speed rear differential is modified to have a neutral position between gear ranges wherein the rotational motion of vehicle drive line is not passed through the rear differential to the vehicle wheels. A drive pulley irrotatably carried by the drive shaft communicates with the PTO assembly by an endless drive belt and the PTO assembly thereafter powers the paper shredder by means of another endless belt.
Pneumatic operation of the modified multi-speed rear differential provides a safety feature because the gear range selector is spring biased toward the neutral position. Accordingly, failure of vehicle pressurized air system causes the modified gear range selector to remain in neutral.
Auxiliary mechanisms that move unshredded and shredded paper are powered by an electrical system comprising two six volt batteries interconnected in series to supply 12 volts of power at high amperage to the electric motors powering the auxiliary mechanisms. Powering the auxiliary mechanisms electrically eliminates the need for hydraulic rams and related fittings to further reduce the weight of the system as compared to known hydraulic PTO systems. Toggle switches and solenoids permit the operator to control movement of the auxiliary mechanisms.
As compared to prior truck mounted hydraulically or mechanically powered paper shredders, the instant invention is less noisy, generates high rotary speed levels, weighs less, is smaller and does not pose an environmental risk of oil spillage. The instant invention allows the truck to carry more shredded paper, operate under more restrictive pollution and noise control ordinances and provide a more efficient paper shredding operation.
My invention does not reside in any of the foregoing features individually but rather in the synergistic combination of all of its structures which necessarily give rise to the functions flowing therefrom as herein specified and claimed.